Did you ever scan this? I have had an MKS-10 for years. I can't remember the last time I used it--other than testing it to see if it works. (It did.) Yesterday I looked under to hood and began to wonder if some additional controls can be added. I searched for the service manual and saw your post. Thanks.
Steve

Great news, albeit 3 years after a few of us were looking for it: The MKS-10 service notes are now available online at a new site: http://www.synfo.nl/pages/servicemanuals.html . (As for me, 2 years ago I gave up and paid approx. $25.00 for a paper copy. )
Steve

The MKS-10 came up in chat today. I dug out a text file with three tidbits taken from the internet several years ago when I was researching the components and architecture for possible modifications. The first one seems to no longer be available.
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BY THE WAY The Roland MKS-10 "Planet P" electric piano MIDI Module, a long forgotten product, can be modified to achieve 16 voice location modulation. Seperate outputs for each of the 16 voices can be found on pin 12 of each of the sixteen IR3109 IC's on the top motherboard. Just find audio ground and you're in like Flynn.

The IR3109 is simply four OTAs and their buffers with a common expo driver. In the JP4 and JP8 Roland simply wired them as four cascaded low pass elements with feedback wrapped around from the fourth stage to the input. The JP-8 has a tap at the second stage for the -12dB output. In JP6 they are wired as two SVFs in cascade - and consequently sound rather different but give HPF and BPF responses.

As we have heard the JP-8's HPF was from a simple BA662 OTA wired as a single pole high pass filter and fitted before the main four pole VCF. Since its not actually tracking the VCOs it has little more effect than a single high pass element in the final output stage of the whole synth. Which is what they did in the Juno-6 et al.

HPF modes can be obtained from cascaded low pass elements in a 'derived' fashion. This is where the various taps are mixed together to form the common filter responses. But to get HPF you need to have the input signal of the filter so that it can be subtracted from the stage outputs. There's a nice section in Electronotes about this - can't remember the number off hand.

But see the Oberheim Xpander for the way they did with the CEM chip. Note that Oberheim used the CEM chip to also mix the two VCO inputs using the CEM's two internal VCAs. Since the internal connection from the VCAs to the first OTA stage is not made available as an output in they had no direct tap to the input of the four stage filter. In high pass mode you need to have this so what they did was to turn the first stage into a buffer stage - this way the first stage tap was actually the input signal to the following three stages. The way they turned the first stage into a buffer is quite clever. Its still a low pass filter, but by changing the timing cap to a very low value, they made the cut-off so high in that stage alone as to make it behave as simple voltage follower. You only get a maximum of a -18dB/oct HP function since you only have three active integrators.

If you are familiar with the eighties Roland synthesizers, then you have likely heard about the dreaded 80017a VCF/VCA chip failure issue. Many synthesizers built by Roland in this period used the 80017a chip: the Juno 106, MKS-30, HS-60 and of course the GR-700. The 80017a is basically a voltage-controlled filter and a voltage-controller amplifier on a single, customized chip made for Roland. The actual components in the 80017a were found as individual elements in the earlier Juno 60 synthesizer: an IR3109 and two BA662 chips. The IR3109 was also used as the heart of the excellent -24 dB low-pass filter in the Roland GR-300.

I just stumbled onto this: http://www.youtube.com/watch?v=p3Q_VPWnG8c .
Evidently it is possible to tap into the audio stream. This guy did it using the headphone jack as an external input. From the video it looks like the preset chosen determines the characteristics of the filter. If anyone here has a youtube account and wants to ask for a schematic or a detailed description of his mods, I'd be interested. (Or, if someone could help me figure out how to do this mod based on the service manual.)

Steve

Quote:

Published on Oct 9, 2012
[Stas Karimov]

This is an old ROLAND module "Planet MKS-10" in which there are only four tools (PIANO, CLAVI, HARPSICHORD, E.PIANO)
My friend occasionally uses it, it also has a built-in analog chorus, flanger and vibrato.
He asked me if it is possible to use (connect) the external instrument to this chorus?
I've made the connection of the external instrument via earphone jack , but it appeared that chorus control is carried out by a digital part of this module and as soon as you release a key on the keyboard, chorus is automatically disconnected. Therefore I've built in a circuit board based on the microcontroller which imitates clicking of a midi key when you plug in the jack of the external tool, and respectively in case of unplugging, it gives a command on key release, it displays a standard green LED.
And it was a pleasant surprise for me to find out that when the external instrument is plugged in and you change sounds on the module (piano, clavi etc.)the tone of the external instrument changes too, and module of a vibrato works also

The MKS-10 came up in chat today. I dug out a text file with three tidbits taken from the internet several years ago when I was researching the components and architecture for possible modifications. The first one seems to no longer be available.

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